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The Review and Nonproliferation

This essay was first published in October 2021, in the second volume of the Centre for Defence Studies series on The Integrated Review in Context: Defence and Security in Focus.

The Integrated Review retains the UK’s twin nuclear policies of maintaining a minimum credible nuclear deterrent and supporting the global nuclear nonproliferation regime. Yet, for the first time since the end of the Cold War, the UK reversed a trajectory of continuous nuclear reductions. By choosing to maintain the deterrent in such a manner

the UK has created a tension between its nonproliferation interests and its security objectives. – Dr Grant Christopher and Alberto Muti

One of the most debated announcements resulting from the Integrated Review was the increase of the UK’s nuclear weapon stockpile ceiling – not the actual number of warheads – from 225 to 260 nuclear warheads. The 16% increase marks the abandonment of an earlier commitment to reduce to below 180 warheads.

The announcement occurred in the context of China, France, Russia and the United States all pursuing significant modernisation and/or expansions of their nuclear programmes. The nuclear-armed states that are not signatories to the NPT, India, Pakistan, Israel and North Korea also are upgrading infrastructure and in some cases expanding their nuclear arsenals. The UK’s increase is relatively smaller than expansions in the other nuclear armed states, and

even after this change, the UK will remain the P5 member with the smallest number of nuclear warheads and the only P5 member with a single delivery system; the Trident II D5 missile aboard a Vanguard-class submarine. – Dr Grant Christopher and Alberto Muti

The Secretary of State for Defence has clarified that the ceiling increase was a response to the ‘evolving security environment’ and that it was meant to maintain a credible deterrent vis à vis advances in Russian ballistic missile defence capabilities - although there are many other viable interpretations.

The UK Government maintains that this marginal increase is not in conflict with the UK’s disarmament obligations under the Nuclear Nonproliferation Treaty (NPT) - and with its nonproliferation stance. Despite these assurances, however, third countries – and especially Non-Nuclear Weapons States (NNWS) will draw their own conclusions on the move, and their reactions could reduce the UK’s standing to work with third countries on shared non-proliferation goals.

The Integrated Review is itself an element of signalling that the UK directs at both allies and rivals. It brought together many strands of the UK’s foreign and defence policy, and questions of deterrence and military strategy, and of how to best communicate the UK’s deterrent stance to possible nuclear-armed adversaries, were considered in great depth. However, it is likely that in many NNWS governments, and especially in smaller countries that are not directly involved or touched by the UK’s grand strategy, this will be primarily seen as a matter of nonproliferation and disarmament policies, rather than one of nuclear deterrence and defence.

Under Article VI of the NPT, the UK as one of the five Nuclear Weapons States (NWS), is required ‘to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament.’ Whether sufficient progress has been made so far, and whether the NWS’ current approaches to nuclear disarmament amount to work in ‘good faith’, however, has been a matter of controversy. Of course, NNWS opinions are divided: most NATO states have remained silent or supportive of the current situation, while other groups, such as the Non-Aligned Movement and the New Agenda Coalition, have been vocal in their criticism.

This debate has an impact on global nonproliferation policies, too, as some non-nuclear weapons states have maintained that disarmament and nonproliferation are interlinked, and progress on one end should be matched by progress on the other. In this context, some states and groups have argued that the constant pursuit of higher nonproliferation standards in the face of what is seen as a failure to make progress on Article VI negotiation is an unsustainable and unfair burden that the NWS – which count some of the richest and more powerful countries in the world – are inflicting on the rest of the international community.

NNWS that are critical of the current status quo have increasingly worked to make their voice heard in a range of international fora, including the United Nations General Assembly’s First Committee and the NPT Review cycle, and in recent years they have negotiated and brought into force the Treaty on the Prohibition of Nuclear Weapons (TPNW), which the UK (as well as the other NWS) does not support. The TPNW provides another avenue outside the usual NPT review conference process to register dissatisfaction and advance nuclear disarmament. The NWS have argued that the treaty undermines their security and the global nonproliferation regime, in particular the NPT.

At the 2015 NPT Review Conference, the NPT States Parties failed to agree on a consensus document, fuelling perceptions of a gridlocked debate and, potentially, a treaty regime in crisis. The 2020 Review Conference, now set to convene on 4-28 January 2022 after delays caused by the COVID-19 pandemic, will open to a climate of high expectations and increased polarisation.

That the UK reversed a course of three-decades of reductions now means that all five NWS under the NPT – and indeed, all nine nuclear-armed states - are expanding and upgrading their nuclear arsenals and infrastructure. – Dr Grant Christopher and Alberto Muti

The impact this will have on the NPT regime is yet to be fully understood.

Before the Review Conference, it should be noted, nuclear disarmament and nonproliferation diplomats will meet in two other key fora, the IAEA General Conference and the UN General Assembly’s Fist Committee, whose next sessions are both set to take place during the last quarter of 2021. These events will provide an occasion for other states to publicly comment on the UK’s move and may set the stage for the NPT negotiations.

Beyond high-level diplomatic meetings, however, there is a wealth of non-proliferation work with direct and practical dimensions that may be impacted by the UK’s decision. One of the key goals of UK non-proliferation policy has been to strengthen international nonproliferation regimes and organisations by encouraging adoption and effective implementation of nonproliferation instruments. These principles are set out in the UK Counter Proliferation Strategies for 2012-2015 and 2016-2020, and have been included in the Integrated Review. The UK has invested in work of this kind through its Counter-Proliferation and Arms Control Centre and has reported on its achievements in this area to the NPT. The UK’s work in these areas includes direct support and contributions to relevant international organisations; crucially, it also includes outreach and work with third countries, with the aim of encouraging universal adoption of nonproliferation instruments and guidelines and strengthening their enforcement and implementation. Key targets for this type of engagement and assistance are non-nuclear weapons states, and especially developing countries with less-advanced internal regulatory systems. This type of work has a tangible, direct impact in supporting and strengthening global nuclear nonproliferation, and it depends on the UK’s ability to work with these countries on shared nonproliferation goals. In the increasingly polarised debate surrounding nuclear nonproliferation and disarmament diplomacy, the decision to raise the nuclear weapons stockpile could reduce this ability.

Few believe the UK increase will cause the NPT to collapse, but the announcement occurs at a difficult time for nonproliferation.

Eroding relationships between the nuclear possessor states accompanies a general reversal of the trend of nuclear arms reductions. – Dr Grant Christopher and Alberto Muti

Recent events have shown that even foundational arms control agreements that took years to negotiate can be unravelled in a few months. In this context, the UK’s decision has consequences beyond defence and deterrence and complicates efforts to preserve and strengthen more than 50 years of international nuclear nonproliferation.


Dr Grant Christopher is a senior researcher in VERTIC’s Verification and Monitoring Programme. He is a former particle physicist with current research interests in the North Korean nuclear programme and the risks associated with emerging technologies.

Alberto Muti is a senior researcher for VERTIC’s Verification and Monitoring Programme. He leads the programme’s work on IAEA Safeguards, Non-proliferation in Iran, and biological investigations.

Disclaimer: VERTIC’s work includes support for adoption and national implementation of nonproliferation instruments; some of this work has been funded by the UK Government.



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